DESCRIPTION: Cardiovascular disease is the number one cause of death and hospitalization throughout the Western World. Reperfusion therapy with fibrinolytic agents has significantly reduced early mortality from acute myocardial infarction and disability from stroke. Despite efforts to enhance the fibrin specificity of genetically engineered fibrinolytic agents, significan bleeding risks have prompted the development of alternative pharmacologic and device approaches for reperfusion. We propose a targeted drug delivery system to improve efficacy and safety. We will engineer a tissue-targeted, filamentous platform technology to deliver inhibitors of plasminogen activator inhibitor-1 (PAI-1). Tissue-specific inhibition of PAI-1 is expected to reduce thrombus burden and vessel reocclusion, while minimizing adverse effects (hemorrhage), and thus improve net clinical benefit. The filamentous structure of the drug carrier has favorable flow dynamics promoting vessel wall and thrombus accumulation, thereby enhancing local endogenous fibrinolysis with reduced bleeding risk. This technology is expected to yield a formulation with high thrombus-specificity and efficacy that will outperform systemic antibody- or small molecule inhibitor-based therapies. A combination of in vitro and in vivo assays will be performed to gain insights into the dynamics of clot-specificity, drug release, efficacy, and potential bleeding risk. A combination of in vivo intravital microscopy, ex vivo imaging, and quantitative tissue analysis will provide detailed information on the efficiency of targeting nanoparticles and PAI-1 inhibitors to the thrombus. We will address whether the nanotherapy improves localized treatment by promoting endogenous fibrinolysis secondary to PAI-1 inhibition and thereby limiting thrombus burden. We will examine the effect of nanotherapy versus free drugs on thrombus growth/stability and carotid artery occlusion time. The effect of PAI-1 inhibition on hemostasis (i.e. tail bleeding time) and blood loss will be assessed. This approach represents a radical shift from current targeting strategies. Nanomedicines targeting the vessel wall could have a significant clinical impact in atherothrombosis, venous thromboembolism, restenosis, and transplant vasculopathy.